The invention relates to charging a rechargeable battery. In particular, the invention relates to charging a rechargeable battery with a portable energy storage device.
Portable, battery-powered devices, such as digital cameras for example, generally depend on a battery-based power supply for their operational power. In particular, battery-based power supplies that employ rechargeable batteries are often used in such portable devices. The rechargeable batteries provide the device with operational power without requiring a continuous connection to a fixed power source, such as an AC electrical outlet, thus allowing for portable operation. The device can be operated from battery power until the rechargeable batteries become depleted. When depleted, the rechargeable batteries are either recharged in situ, or removed from the device for recharging and may be replaced with fully charged, replacement batteries.
Conventionally, to effect in situ battery recharging, an alternating current (AC) adapter and an associated power cord or power cords are employed. Typically, the AC adaptor is plugged into an available AC electrical power outlet and the associated power cable is plugged into a power input port of the device. The AC adaptor converts AC energy available from the electrical outlet into direct current (DC) energy that is then fed into the device to charge the batteries inside the device. During recharge, the device is fixed or tethered to the AC electrical power outlet. Once recharged, the power cable may be disconnected and the device is once again portable, deriving operational power from the charged batteries.
Unfortunately, devices that utilize conventional battery-based power supplies and in situ recharging often suffer from a relatively slow recharge time of the battery. In particular, most conventional rechargeable batteries typically require about one hour to several hours to charge. Even modem, so-called xe2x80x98rapid chargingxe2x80x99 batteries may take anywhere from several minutes to nearly an hour to acquire and store an energy charge level sufficient to power to the device for a xe2x80x98normalxe2x80x99 operating period. Thus, the portable device is not truly portable during battery charging, since an electrical connection to a fixed energy source (e.g., the AC power outlet) tethers the device during in situ recharging.
In addition, many practical situations make in situ charging difficult if not impossible. For example, an AC outlet may be available to a user of a portable battery powered device for only a very limited amount of time (e.g., while traveling). Thus, while the AC electrical outlet is temporarily available, there may be insufficient time to charge the battery once it has become depleted.
Conventionally, a spare fully charged battery is often carried along with the AC adapter and cable. The spare battery may be inserted in the device to replace a depleted battery when in situ charging is not possible or is inconvenient. Spare batteries add to the overall weight of the device thus decreasing the xe2x80x98portabilityxe2x80x99 of such a device. Moreover, spare batteries only postpone the inevitable need for access to the fixed energy source for a time sufficient to effect battery charging.
Accordingly, it would be advantageous to have a way to facilitate battery charging that did not depend on having access to a fixed energy source for a time sufficient to effect battery charging. Such a way of battery charging would solve a long-standing need in the area of portable, battery-powered devices.
The present invention provides remote or untethered charging of a rechargeable battery used with a portable battery-powered device. In particular, the present invention provides untethered charging either as in situ charging of the battery within the device or as charging of the battery that has been removed from or is external to the device. Moreover, the present invention charges the battery without a need for a connection to a conventional, fixed external energy source during the time the battery is being charged. As such, the present invention provides an independent, xe2x80x98untetheredxe2x80x99, xe2x80x98unpluggedxe2x80x99 or effectively a xe2x80x98cordlessxe2x80x99 means of battery charging.
In an aspect of the invention, a battery charger is provided that acquires and stores energy. The stored energy is used to charge a battery of a portable battery-powered device. The battery charger comprises means for converting energy acquired from an external energy source and means for storing energy connected to an output of the power converting means. The power converter means converts the acquired energy into a form suitable for storing in the energy storing means. Once stored, the energized battery charger may be disconnected from the external energy source. The energy is stored by the energized battery charger until used to charge a rechargeable battery.
The storage of energy from the external energy source is effectively independent of battery charging according to the present invention. Moreover, the energized battery charger provides a means for untethered charging of the rechargeable battery. During untetherered charging, the energized battery charger is connected to the rechargeable battery and the energy stored in the energized battery charger is used to charge the battery.
In some embodiments, the battery is charged in situ or while the battery is within the battery-powered device. In other embodiments, the battery is removed from the device prior to charging the battery using the energized battery charger of the present invention. In all of the embodiments described herein, the battery charger advantageously is not or need not be electrically connected to, plugged into, or otherwise restrained by, constrained by or tethered to, a fixed external source of energy during battery recharging. Thus, the battery charger of the present invention may be considered a xe2x80x98cordlessxe2x80x99 or xe2x80x98untetheredxe2x80x99 battery charging means. In other aspects of the present invention, a battery charging system and a method of charging a rechargeable battery are provided.
Advantageously, the battery charging means of the present invention provides a user of a battery-powered device with more battery recharging flexibility than the user had before the present invention. En essence, the present invention frees the battery-powered device and/or battery from an attachment to the fixed external energy source during charging since the battery is charged using energy stored in the energized charger instead of being charged while the charger is connected to the fixed external energy source, such as an AC outlet or a DC outlet or port. Moreover, the battery charger of the present invention enables a user of the portable device to acquire and store sufficient energy in a matter of seconds or minutes. Preferably, once energized the charger possesses sufficient energy to charge a battery and the user is free to recharge the battery with the energized battery charger at the user""s convenience. Certain embodiments of the present invention have other advantages in addition to and in lieu of the advantages described hereinabove. Theme and other features and advantages of the invention we detailed below with reference to the following drawings.